Materials Data on Mg2GeSe4 by Materials Project

Abstract

Mg2GeSe4 is Spinel-like structured and crystallizes in the orthorhombic Pnma space group. The structure is three-dimensional. there are two inequivalent Mg2+ sites. In the first Mg2+ site, Mg2+ is bonded to six Se2- atoms to form MgSe6 octahedra that share corners with eight MgSe6 octahedra, corners with four equivalent GeSe4 tetrahedra, edges with two equivalent MgSe6 octahedra, and an edgeedge with one GeSe4 tetrahedra. The corner-sharing octahedra tilt angles range from 47–57°. There are a spread of Mg–Se bond distances ranging from 2.72–2.80 Å. In the second Mg2+ site, Mg2+ is bonded to six Se2- atoms to form MgSe6 octahedra that share corners with four equivalent MgSe6 octahedra, corners with two equivalent GeSe4 tetrahedra, edges with four MgSe6 octahedra, and edges with two equivalent GeSe4 tetrahedra. The corner-sharing octahedra tilt angles range from 51–57°. There are a spread of Mg–Se bond distances ranging from 2.73–2.78 Å. Ge4+ is bonded to four Se2- atoms to form GeSe4 tetrahedra that share corners with six MgSe6 octahedra and edges with three MgSe6 octahedra. The corner-sharing octahedra tilt angles range from 59–62°. There are one shorter (2.37 Å) and three longer (2.40 Å) Ge–Se bond lengths. There are three inequivalent Se2- sites. In the first Se2- site, Se2- is bonded to three Mg2+ and one Ge4+ atom to form distorted corner-sharing SeMg3Ge trigonal pyramids. In the second Se2- site, Se2- is bonded in a rectangular see-saw-like geometry to three Mg2+ and one Ge4+ atom. In the third Se2- site, Se2- is bonded in a rectangular see-saw-like geometry to three Mg2+ and one Ge4+ atom.